Cell Differentiation, Proliferation, and Apoptosis

Not only is calcitriol an important determinant for the differentiation of osteo-clastprecursor cells, it also directs the differentiation and maturation of normal and leukemic cells into monocytes, and potentiates apoptosis induced by 9-cis-retinoic acid, although it does not induce apoptosis itself. This suggests the possibility of what has been called maturation therapy for leukemia rather than conventional chemotherapy (James et al., 1999). 

Calcitriol induces terminal differentiation of skin keratinocytes in culture, an action that has been exploited in the treatment of psoriasis (Section 3.6.2). In keratinocytes in culture, both calcium and calcitriol are required for differentiation. Cells lacking the calcium-sensing receptor or phospholipase C-y 1 fail to differentiate in response to calcium or calcitriol, suggesting that in 

Hair follicles also have calcitriol receptors and type 11 vitamin D-resistant rickets (Section 3.4.2), which is caused hy lack of calcitriol receptor function, is associated with total alopecia, suggesting that calcitriol has a role in their development. 

Adipocytes have vitamin D receptors, and there is evidence that vitamin D may act as a suppressor of adipocyte development (Kawada et al., 1996). It has been suggested that vitamin D inadequacy may be a factor in the development of the metabolic syndrome ( syndrome X, the combination of insulin resistance, hyperlipidemia, and atherosclerosis associated with abdominal obesity). Sunlight exposure, and hence vitamin D status, may be a factor in the difference in incidence of atherosclerosis and myocardial infarction between northern and southern European countries in addition to effects on adipocyte development, calcitriol also enhances insulin secretion through induction of calbindin-D (Section 3.3.7.1), and there is some evidence vitamin D supplements can improve glucose tolerance (Boucher, 1998). 

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AP-1 is a transcription factor involved in the regulation of cell growth, differentiation, proliferation, and apoptosis. AP-1 exists as homo- and hetmxlim and is activated by growth factors, cytokines, and cellular stress, c-jim and c-fos are two... 

Tissues consist of smaller repeating units on the scale of hundreds of micrometers in vivo. The 3D architecture of these repeating tissue units underlies the coordination of multicellular processes, emergent mechanical properties, and integration with other organ systems via the microcirculation [11], Furthermore, the local cellular environment presents biochemical, cellular, and physical stimuli that orchestrate cellular fate processes such as proliferation, differentiation, migration, and apoptosis. Thus, successful fabrication of a fully functional tissue must include both an appropriate environment for cell viability and function at the microscale... 

In other brain regions such as the cerebellum, there are cells simultaneously undergoing proliferation, differentiation, migration, and apoptosis. Thus, the contribution of these basic cellular processes to organ development can vary temporally across organ regions and in relation to each other. 

CDX-2 CDX-2 is a caudal type homeobox gene, which encodes a 33-kDa 311-amino-acid nuclear protein. C DX-2 is an intestine-specific transcription factor expressed in the early intestinal development stage supposed to be involved in the differentiation, adhesion, proliferation and apoptosis of intestinal epithelial cells. 

Pituitary adenomas MiR-26a,miR-26b, miR-197,miR-103,miR-103-2.miR-192,miR-149, and miR-24 up MiR-128a,miR-136,miR-132,miR-223,miR-7-3,let-7a-l,let-7f-l,miR-192-2j3,miR-9-3,miR-7-l,let-7e,miR-212,miR-164,miR-138-2,miR-7-3,sind miR-100-112domi Microarray, confirmed by real-time RT-PCR Several differentially expressed miRNAs are involved in cell proliferation and apoptosis 150... 

In recent years, miRNAs have been shown to influence a variety of cellular processes of key importance, including cellular differentiation and maintenance of a differentiation state, developmental timing, proliferation and apoptosis (Alvarez-Garcia and Miska 2005 Zhang et al. 2007). Since deregulated cell death and proliferation are hallmarks of many types of carcinomas, it is not surprising that, on the one hand, alterations in miRNA may lead to carcinogenesis, and, on the other hand, many miRNAs are found to be abnormally expressed in clinical cancer samples. 

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